Normality (N) is a unit of concentration in chemistry defined as the number of gram equivalents of solute dissolved per litre of solution. It is a reaction-specific concentration — the equivalent depends on the type of reaction (acid-base, redox, or precipitation). Normality was widely used in older analytical chemistry and is still tested in class 11–12 and competitive exams.
Normality (N) = gram equivalents of solute / volume of solution (litres)
N = Molarity × n-factor
n-factor for acids = number of H⁺ ions donated (basicity)
n-factor for bases = number of OH⁻ ions donated (acidity)
H₂SO₄: 1M = 2N; HCl: 1M = 1N; NaOH: 1M = 1N
KMnO₄ (acidic medium): n-factor = 5
Normality is reaction-specific; molarity is not
Definition: Normality (N) = Number of gram equivalents of solute / Volume of solution in litres
Formula: N = (Weight of solute / Equivalent weight of solute) / Volume of solution (in litres)
OR: N = Molarity (M) × n-factor
Where:
Unit: N (or eq/L, equivalents per litre)
Acids:
Bases:
Salts (in acid-base context):
Oxidising agents:
Example 1: Find normality of 9.8 g of H₂SO₄ in 500 mL solution.
Example 2: 1 M H₂SO₄ → Normality = ?
Example 3: 1 M NaOH → Normality = ?
Molarity (M):
Normality (N):
Key relationship: N = M × n-factor
For compounds where n-factor = 1 (e.g., HCl, NaOH): N = M For compounds where n-factor = 2 (e.g., H₂SO₄): N = 2M
Important: Normality of a solution is not fixed — it changes with the reaction context. For example, H₃PO₄ can have N = M, N = 2M, or N = 3M depending on how many protons it donates in a reaction.
Normality (N) is the number of gram equivalents of solute dissolved per litre of solution. It is calculated as N = Molarity × n-factor. Normality is reaction-specific — the n-factor changes depending on whether the compound acts as an acid, base, oxidising agent, or reducing agent.
Normality = Molarity × n-factor. For acids, n-factor = number of H⁺ ions donated. For bases, n-factor = number of OH⁻ ions. For example: 1 M H₂SO₄ = 2 N (n=2), 1 M HCl = 1 N (n=1), 1 M NaOH = 1 N (n=1).
In acidic medium, KMnO₄ acts as an oxidising agent. Mn changes from +7 to +2 (change = 5). So n-factor = 5. Therefore, 1 M KMnO₄ (acidic) = 5 N. In neutral/alkaline medium, Mn changes to +4 (change = 3), so n-factor = 3.
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